Lesson 6 - Growth and Yield Flashcards
what is growth and yield, describe each one
body of information and techniques concerned with estimating future conditions for forest stands
growth: the change in some characteristic (attribute) of a tree or stand over time
yield: the quantity of some attribute of a tree or stand that is present at some point in time
explain MAI, CAI and PAI
mean annual increment: average growth of a tree or stand (yield at some age/age)
current annual increment: yearly growth, the difference in yield of two consecutive years
periodic annual increment: the average growth rate calculated over a specified time rate
how do CAI and MAI interact
yield curve is sigmoidal, characterized by three growth stages
youth characterized by a steady increase in both the CAI and MAI
maturity characterized by a slowing of the CAI coupled with an increasing MAI
senescence characterized by decreasing CAI and MAI
what is the culimination age
the age at which MAI is maximized
- stands managed with this as the rotation age, wood fibre is maximized
How do we use growth and yield information
- determining aac
- updating inventories
- choice of silviculture treatment
- returns on investments
- choosing rotation age
- long term planning
- comparison of production
What are the factors that affect the growth of trees
species, site quality, density, insects/diseases/damaging agents, managerial inputs
TSP vs PSP and what are they used for
temporary sample plot - measure the yield of stands, measured once
permanent sample plot - measure growth, revisited on many occasions
What are yield tables and what are the different types
display stand conditions at various ages in tabular format
normal yield tables: based on data from fully stocked stand
empirical yield tables: based on data from stands with average stocking
variable density yield tables: incorporate some measure of stand density
managed stand yield tables: predict growth in stands that have been silviculturally treated in some fashion
How can CAI be approximated
CAI = dbh x HT x W
W = width in metres of the last annual ring
how can MAI be approximated
MAI = (dhb2 x HT)/(4 x age)
What are some indicators of density
stems per ha, basal area per ha, average crown closure
how do you determine site quality
direct measures:
- estimation from historical yield records
- estimation based on stand volume data
- estimation based on stand height data
indirect measures:
- estimation from overstory species relationships
- estimation from lesser vegetation characteristics
- estimation from topographic, climatic, and edaphic factors
what is site index
an indicator of site quality, defined as the average height of a specified portion of the stand at some reference age
what assumptions underlie the use of site index
- the height of specific trees (usually dominants) is an indicator of site potential. the height of such trees is not influenced by non-site factors such as density and sire preparation
- site index is constant over time
- directions for calculating site index have been followed correctly in the field
When to use site index
- the species of interest must be present in the stand in sufficient numbers
- the stand must be within a specified age range
- the stand should be even-aged